Indonesian police found only a stash of bomb-making materials after arresting 6 men suspected of planning a rocket attack on Singapore from a nearby island, a senior officer said on Saturday , But police spokesman Boy Rafli Amar said a search was on for more members of a gang now believed to be part of a wider network taking instructions from ISIS militant to launch attacks across Southeast Asia , Singapore called for heightened vigilance a day after the suspected militants were rounded up. It said their plot to target Marina Bay, a glittering downtown waterfront, showed the city-state needed to defend its multiple points of entry , The 6 suspected militants were detained on Friday in dawn raids on Batam island, about 15 km south of Singapore, where police believe the men planned to fire the rockets from.